﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;

namespace clawSoft.clawPDF.Core.Helper
{
    public class HttpHelper
    {
        /// <summary>
        /// HttpUploadFile
        /// </summary>
        /// <param name="url"></param>
        /// <param name="files"></param>
        /// <param name="data"></param>
        /// <param name="encoding"></param>
        /// <returns></returns>
        public static string HttpUploadFile(string url, string[] files, Dictionary<string, string> data, Encoding encoding)
        {
            //必须
            string boundary = DateTime.Now.Ticks.ToString("X");
            //必须的

            //form 开始标志
            byte[] boundarybytes = Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");

            //form 结尾标志
            byte[] endbytes = Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");

            //1.HttpWebRequest
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);

            request.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary;
            request.Method = "POST";
            request.KeepAlive = true;
            request.Credentials = CredentialCache.DefaultCredentials;
            request.Timeout = 60 * 1000;

            using (Stream stream = request.GetRequestStream())
            {
                //传递参数模板 Content-Disposition:form-data;name=\"{0}\"\r\n\r\n{1}
                //1.1 key/value
                string formdataTemplate = "Content-Disposition:form-data;name=\"{0}\"\r\n\r\n{1}";
                //传递参数
                if (data != null)
                {
                    foreach (string key in data.Keys)
                    {
                        //传递参数开始标识
                        stream.Write(boundarybytes, 0, boundarybytes.Length);

                        string formitem = string.Format(formdataTemplate, key, data[key]);

                        byte[] formitembytes = encoding.GetBytes(formitem);

                        stream.Write(formitembytes, 0, formitembytes.Length);
                    }
                }

                //上传文件模板
                //1.2 file
                string headerTemplate = "Content-Disposition:form-data;name=\"{0}\";filename=\"{1}\"\r\nContent-Type:application/octet-stream\r\n\r\n";

                byte[] buffer = new byte[6 * 1024 * 1024];

                for (int i = 0; i < files.Length; i++)
                {
                    //上传文件标识
                    stream.Write(boundarybytes, 0, boundarybytes.Length);

                    string header = string.Format(headerTemplate, $"file", Path.GetFileName(files[i]));

                    byte[] headerbytes = encoding.GetBytes(header);

                    stream.Write(headerbytes, 0, headerbytes.Length);

                    //将文件流读入到请求流中
                    using (FileStream fileStream = new FileStream(files[i], FileMode.Open, FileAccess.Read))
                    {
                        int r = fileStream.Read(buffer, 0, buffer.Length);
                        stream.Write(buffer, 0, r);
                    }
                }

                //form 结束标志
                //1.3 form end
                stream.Write(endbytes, 0, endbytes.Length);
            }
            //2.WebResponse
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            using (StreamReader stream = new StreamReader(response.GetResponseStream()))
            {
                string result = stream.ReadToEnd();
                return result;
            }
        }
    }
}
